A computed tomography (CT) scan uses X-rays to make pictures of the head and face.
During the test, you will lie on a table that is attached to the CT scanner, which is a large doughnut-shaped machine. Your head will be positioned inside the scanner. The CT scanner sends X-rays through the head. Each rotation of the scanner provides a picture of a thin slice of the head and face. One part of the scanning machine can tilt to take pictures from different positions. All of the pictures are saved as a group on a computer. They also can be printed.
In some cases, a dye called contrast material may be put in a vein (IV) in your arm or into the spinal canal. The dye makes structures and organs easier to see on the CT pictures. The dye may be used to check blood flow and look for tumours, areas of inflammation, or nerve damage.
A CT scan of the head can give some information about the eyes, facial bones, air-filled cavities (sinuses) within the bones around the nose, and the inner ear. If these areas are of concern, a specific CT scan of the area is usually done.
A CT scan of the head may be used to evaluate headaches.
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A CT scan of the head is done to:
CT scans of the eyes, facial area, and sinuses may be done to:
Before the CT scan, tell your doctor if you:
Arrange for someone to take you home in case you get a medicine to help you relax (sedative) for the test.
Talk to your doctor about any concerns you have regarding the need for the test, its risks, or how it will be done. To help you understand the importance of this test, fill out the medical test information form( What is a PDF document? ).
A CT scan is usually done by a radiology technologist. The pictures are usually read by a radiologist, who writes the report. Other doctors also may review a CT scan.
You may need to take off any jewellery, glasses, and hearing aids. Wear comfortable, loose-fitting clothes.
During the test, you will lie on a table that is attached to the CT scanner. Straps will hold your head still, but your face will not be covered.
The table slides into the round opening of the scanner, and the scanner moves around your body. The table will move while the scanner takes pictures. You may hear a click or buzz as the table and scanner move. It is very important to lie still during the test.
During the test, you may be alone in the scan room. But the technologist will watch you through a window. You will be able to talk to the technologist through a two-way intercom.
The test will take about 30 to 60 minutes. Most of this time is spent getting ready for the scan. The actual scan only takes a few seconds.
The test will not cause pain. The table you lie on may feel hard, and the room may be cool. It may be hard to lie still during the test.
Some people feel nervous inside the CT scanner.
If a medicine to help you relax (sedative) or dye (contrast material) is used, an IV is usually put in your hand or arm. You may feel a quick sting or pinch when the IV is started. The dye may make you feel warm and flushed and give you a metallic taste in your mouth. Some people feel sick to their stomach or get a headache. Tell the technologist or your doctor how you are feeling.
The chance of a CT scan causing a problem is small.
A computed tomography (CT) scan uses X-rays to make detailed pictures of structures inside the body.
Complete results usually are ready for your doctor in 1 to 2 days.
The brain and blood vessels and bones of the skull and face are normal in size, shape, and position.
No foreign objects or growths are present.
No bleeding or collections of fluid are present.
A growth, such as a tumour, or bleeding is present in or around the brain. Foreign objects, such as glass or metal fragments, are present. The bones of the skull or face are broken (fractured) or look abnormal. Nerves leading to or from the brain are damaged or pinched.
A collection of fluid is found, which may mean bleeding in or around the brain.
An aneurysm is present.
The openings in the brain (ventricles) through which cerebrospinal fluid flows into the spine are enlarged. An area of the brain shows swelling ( edema) or other changes that may mean a stroke.
The sinuses are filled with fluid or have a thick lining.
The following may stop you from having the test or may change the test results:
Einstein AJ, et al. (2007). Estimating risk of cancer associated with radiation exposure from 64-slice computed tomography coronary angiography. JAMA, 298(3): 317–323.
Other Works Consulted
Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
Pagana KD, Pagana TJ (2010). Mosby's Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby.
Pearce MS, et al. (2012). Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: A retrospective cohort study. Lancet, 380(9840): 499–505.
U.S. Food and Drug Administration (2008). FDA preliminary public health notification: Possible malfunction of electronic medical devices caused by computed tomography (CT) scanning. Available online: http://www.fda.gov/MedicalDevices/Safety/AlertsandNotices/PublicHealthNotifications/ucm061994.htm.
ByHealthwise StaffPrimary Medical ReviewerAdam Husney, MD - Family MedicineBrian O'Brien, MD, FRCPC - Internal MedicineE. Gregory Thompson, MD - Internal MedicineMartin J. Gabica, MD - Family MedicineHoward B. Schaff, MD - Diagnostic Radiology
Current as ofOctober 9, 2017
Current as of: October 9, 2017
Adam Husney, MD - Family Medicine
& Brian O'Brien, MD, FRCPC - Internal Medicine & E. Gregory Thompson, MD - Internal Medicine & Martin J. Gabica, MD - Family Medicine & Howard B. Schaff, MD - Diagnostic Radiology
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